Lua script to set the COM1 standby frequency (FSUIPC6 and P3Dv5)

[Isak]

*** Moved from FSUIPC7 / MSFS sub-forum to main support forum ***

Hi everyone,

I’m currently working on a small Arduino project that allows me to input a radio frequency using a keypad. The frequency is displayed on an LCD screen. For example, if I type 120.800 and press the "#" key, the following appears in the serial monitor:

COM1SB 120.800

What I want to achieve is setting the COM1 standby frequency in the simulator. I believe I’ll need to write a Lua script to detect the string "COM1SB", extract the frequency, and send it to the simulator using ipc.control.

Am I correct that 66371 (COM_STBY_RADIO_SET) is the right ipc.control command to use? Could someone share an example of a Lua script that would accomplish this?

Best regards,
Isak

 

Edited October 23, 2024 by John Dowson
Moved to main support forum, key file removed

[John Dowson]

First, you posted in the sub-forum for FSUIPC7 / MSFS - please use the main forum for all other versions of FSUIPC, not the specific sub-forum for FSUIPC7.
You also attached the trial license/key file for FSUIPC7 for some reason...I have removed that.

16 hours ago, Isak said:

Am I correct that 66371 (COM_STBY_RADIO_SET) is the right ipc.control command to use? Could someone share an example of a Lua script that would accomplish this?

Yes, that is the correct control/event, but be aware that the parameter for that control is in BCD16 format (Binary-encoded decimal), so to set to 120.80 you would use:
     ipc.control(66371, 0x2080)
(the leading 1 is assumed).

17 hours ago, Isak said:

I believe I’ll need to write a Lua script to detect the string "COM1SB", extract the frequency,

That is the difficult bit. You would need to register a function to receive key presses (using the event.key function) for the keys 'C'. 'O', 'M'. '1', ' ', 'S', 'B', ',' , and all the digits, then keep track of everything entered and in the correct order....I really can't recommend doing it this way....

Maybe take a look at this user' contribution, which is a lua script to allow keyboard entry for radios (as well as obs and AP). Its for FSUIPC4, but should work with FSUIPC5, although some small modifications may be needed: 

 

 

John

[Isak]

Hi John,

Thank you for your detailed response and for pointing out my mistake with the forum and the license file. Apologies for that!

I appreciate the clarification on the BCD16 format. That example definitely helps.

Regarding the Lua script for detecting "COM1SB," I can see how handling all those key presses might get complicated. I'll check out the Lua script you mentioned for keyboard entry of radios and see if I can adapt it to my needs.

Thanks again for your help!

Best regards,
Isak

[John Dowson]

I am not sure how you are getting the input to set your LCD display, but It may be easier to use the ipc.ask lua function to get this user input / com frequency in one go (rather than monitoring keyboard input via event.key), and then use the value received to set your LCD display (however that is done!) and send the control to set in the sim. You would need to run such a script on a specific key combination or button press.
Cheers,

John

[John Dowson]

...and if you have written your own program to drive the LED connected to the arduino, you could use the FSUIPC SDK to just write the com1 standby frequency to offset 0x05CC (or 0x311A).

Note that you can also use the following control to set the frequency using Hz rather than in BCD format:

67363   COM1_STBY_RADIO_HZ_SET

[Isak]

Thank you for the insights, John! I'm currently traveling, but as soon as I'm back, I'll share my Arduino code and my current Lua script attempt. Looking forward to any additional feedback you might have once I post those details.

Cheers,

Isak

[Isak]

Here is the working Arduino code that allows me to type in a frequency, which then shows up on the LCD screen. When I press the "#" key, the frequency is sent over the serial port as shown below (output from the serial monitor):

17:12:34.711 -> COM1SB 120.800
 

#include <Keypad.h>
#include <LiquidCrystal.h>

// Initialize the LCD connected to pins 9, 8, 7, 6, 5, 4 on Arduino
LiquidCrystal lcd(9, 8, 7, 6, 5, 4);

// Keypad settings
const byte ROWS = 4; // four rows
const byte COLS = 4; // four columns
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {A0, A1, A2, A3}; 
byte colPins[COLS] = {A4, A5, A6, A7}; 

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

String frequency = "1";  // Pre-define the first digit as '1'

void setup() {
  lcd.begin(20, 4); 

  // Turn off the display:
  lcd.noDisplay(); delay(500);
  // Turn on the display:
  lcd.display();
  
  // Initial LCD message:
  lcd.setCursor(0, 0);
  lcd.print("Keypad Radio");
  delay(4000);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Frequency to send:");
  
  Serial.begin(115200); //start checking serial connection
}

void loop() {
  char key = keypad.getKey();
  if (key) {
    if (key == '#') {
      sendFrequencyToSim();
      frequency = "1";  // Reset to '1' after sending
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Frequency to send:");
    } else if (key == '*') {
      if (frequency.length() > 1) {  // Ensure '1' stays as the first digit
        frequency.remove(frequency.length() - 1); // Remove last digit
        
        // Clear the previous frequency display and update it
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Frequency to send:");
        lcd.setCursor(0, 2);
        lcd.print(formatFrequency(frequency));
      }
    } else if (isDigit(key)) {
      if (frequency.length() < 6) {  // limit to 6 digits (including '1')
        frequency += key;
        
        // Update the LCD with the new frequency
        lcd.setCursor(0, 2);
        lcd.print(formatFrequency(frequency));
      }
    }
  }
}

String formatFrequency(String freq) {
  // Automatically add the decimal point at the right place
  if (freq.length() >= 4) {  // Adjusted to account for the pre-defined '1'
    return freq.substring(0, 3) + "." + freq.substring(3);
  }
  return freq;  // If less than 3 digits, no decimal
}

void sendFrequencyToSim() {
  String formattedFrequency = formatFrequency(frequency);  // Add the decimal point
  Serial.print("COM1SB ");  // Add COM1SB tag
  Serial.println(formattedFrequency);  // Send formatted frequency (with decimal)
}

Now, I am struggling with the Lua script. I’m not very experienced with coding and would really appreciate any guidance. My current attempt connects to the serial port, but the frequency is not being set:

----------------------------------------------------------------
----------------------------------------------------------------
dev = com.open("COM6", 115200, 0)  -- Open COM port with baud rate 115200
----------------------------------------------------------------
----------------------------------------------------------------

-- Display a message to indicate that the script is running
ipc.display("Lua script is running...", 3)  -- Message stays for 3 seconds

function processInput()
    local datastring = com.read(dev, 256, 100)  -- Read up to 256 bytes from the serial port, 100ms timeout
    if datastring ~= "" then
        ipc.display("Data received: " .. datastring, 2)  -- Display the received data for debugging

        -- Example of parsing the received string to set COM1 standby frequency
        if datastring:match("^COM1SB") then
            local frequency = tonumber(datastring:sub(8)) * 1000  -- Extract frequency and convert to Hz
            ipc.control(67363, frequency)  -- COM1_STBY_RADIO_HZ_SET
            ipc.display("COM1 standby frequency set to: " .. frequency, 3)
        end
    end
end

-- Main loop to continuously check for serial input
while true do
    processInput()  -- Call the function to process any incoming serial data
    ipc.sleep(100)  -- Small delay to avoid high CPU usage
end

Cheers,

Isak

[John Dowson]

16 minutes ago, Isak said:

Now, I am struggling with the Lua script. I’m not very experienced with coding and would really appreciate any guidance. My current attempt connects to the serial port, but the frequency is not being set:

Is the script receiving any data? Try debugging the script, by either starting it with LuaDebug or by setting Debug / Trace Lua plugins in the FSUIPC logging tab.

 But it would be better to update your C code and use the FSUIPC SDK to update the offset with the COM! stndby frequency. Take a look in the SDK subfolder, at the UIPC64_SDK_C_version2 toolkit. You can use this to update FSUIPC offsets, which will trigger the controls to set the values in the FS,

John

[Isak]

So, if I change the C code and use the FSUIPC SDK to update the offset with the COM! stndby frequency, there is no need for a lua script?

[Isak]

Here is the FSUIPC6.log that shows what happens when I start the script and try to send/set a frequency. The script is called RadioTest.lua.

FSUIPC6.log

[John Dowson]

1 hour ago, Isak said:

So, if I change the C code and use the FSUIPC SDK to update the offset with the COM! stndby frequency, there is no need for a lua script?

Yes.

49 minutes ago, Isak said:

Here is the FSUIPC6.log that shows what happens when I start the script and try to send/set a frequency. The script is called RadioTest.lua.

You are using Linda so that log is very difficult to interpret...set Log Lua plugins separately and show me the log file for the script only, and also attach the script.

John

[Isak]

Here I have attached the separate log-file and the lua script.

Isak

RadioTest.lua RadioTest.log

[John Dowson]

Quote

    local datastring = com.read(dev, 256, 100)  -- Read up to 256 bytes from the serial port, 100ms timeout

This is not correct - the documentation states:

str, n = com.read(handle,max,min)

so your call will always return a null string until at least 100 characters are read, Please see the documentation on com.read (see below)  - you need something like (with no minimum):

function processInput()
    local datastring, length = com.read(dev, 256)  -- Read up to 256 bytes from the serial port
    if length then
        ipc.display("Data received: " .. datastring, 2)  -- Display the received data for debugging
        ipc.log("Data received: '" .. datastring .. "' [" .. length .. "]") -- log to file
        -- Example of parsing the received string to set COM1 standby frequency
        if datastring:match("^COM1SB") then
            local frequency = tonumber(datastring:sub(8)) * 1000  -- Extract frequency and convert to Hz
            ipc.control(67363, frequency)  -- COM1_STBY_RADIO_HZ_SET
            ipc.display("COM1 standby frequency set to: " .. frequency, 3)
            ipc.log("COM1 standby frequency set to: " .. frequency)  -- log to file
        end
    end
end

John

str, n = com.read(handle,max) str, n = com.read(handle,max,min) str, n = com.read(handle,max,min, term)

Reads up to 'max' bytes from the port, returning them as a string in 'str' with the number actually read returned in 'n'. If the 'min' parameter is also given, this returns a null string and n=0 until at least that minimum number of bytes are available. It does not block waiting for them. If you specify -1 as the minimum then the terminating character ('term') must be seen before the function returns a non-zero result, unless of course the 'max' size is reached first. The 'term' parameter specifies an ASCII value (0 to 255) which is to be treated as a terminator for each block. This character is included in the returned count and string. Note that you can use the event library function, event.com to perform reads and call your Lua back when there is data to process. This can be more efficient and tidier than a program which uses continuous loops to scan the input.

 

[Isak]

With the code you suggested (with no minimum), I now receive a SimConnect message when I try to send a frequency.

For example, when I type in 120.800 and send it, the following message appears:

SimConnect Message Window
COM1 standby frequency set to: 120800

Or if I send 118.100, I get:

SimConnect Message Window
COM1 standby frequency set to: 118100

However, the COM1 standby frequency in the aircraft does not actually update. I am using the standard Lockheed Martin AC-130H aircraft for testing. Any insights on what might be missing?

I attached the script and log file again.

Isak

RadioTest.log RadioTest.lua

[John Dowson]

120.800 is in MHz, not KHz, so multiply by 1000000 not 1000 here:
    

local frequency = tonumber(datastring:sub(8)) * 1000000  -- Extract frequency and convert to Hz

[Isak]

I just got back from work and tried multiplying by 1000000, and it worked! Thank you so much for helping me out. Now, I’m planning to optimize the Lua script further by using the event.com function to handle reads and call back when there’s data to process. I’ll also look into modifying the C code to send the frequency directly to the simulator.

Again, thank you so much for your help!

Cheers,
Isak

[John Dowson]

Glad its now working. Yes, using event.com is much more efficient.

10 hours ago, Isak said:

I’ll also look into modifying the C code to send the frequency directly to the simulator.

That is probably a better long-term solution, as you are already writing your own code to drive the LCD. Via the SDK, you can either write the COM1 standby frequency (in Hz) to offset 0x05CC (as a 4-byte int), or you can use offset 0x3110 which operates a facility to send any control to the FS.

Cheers,

John

[Isak]

Hi again,

Now I would like to also be able to set the NAV1 Standby frequency in the same manner.
The FSUIPC6.log file shows the following string when I send the NAV1 frequency 109.2:

314110 LUA.7: Local: datastring = NAV1SB 109.2

However in the simulator the NAV1 freqeuncy is not beeing set. Here is my lua script:

dev = com.open("COM6", 115200, 0)  -- Open COM port with baud rate 115200

ipc.display("Lua script is running...", 3)

function processInput()
    local datastring, length = com.read(dev, 256)
    if length then
        ipc.display("Data received: " .. datastring, 2)
        ipc.log("Data received: '" .. datastring .. "' [" .. length .. "]")

        -- Check if data is for NAV1
        if datastring:match("^NAV1SB") then
            local frequencyStr = datastring:sub(8)  -- e.g., "113.45"
            local bcdValue = convertToBCD(frequencyStr)
            
            -- Write to NAV1 standby frequency offset (0x0352)
            ipc.writeUD(0x0352, bcdValue)
            
            ipc.display("NAV1 standby frequency set: " .. frequencyStr, 3)
            ipc.log("NAV1 standby frequency BCD: " .. string.format("0x%X", bcdValue))
        end
    end
end

-- Convert frequency to 4-digit BCD (leading '1' assumed)
function convertToBCD(freq)
    local cleanFreq = freq:gsub("%.", "")  -- Remove the decimal
    local bcd = tonumber(cleanFreq, 10)    -- Convert to integer
    return bcd
end

while true do
    processInput()
    ipc.sleep(100)
end

Any ideas on how to get it working?

Cheers,
Isak

[John Dowson]

9 hours ago, Isak said:

Any ideas on how to get it working?

First, offset 0x0352 is for Nav2 active frequency - Nav1 active is at 0x0350 and Nav1 standby is at 0x311E..

To debug the script, you can use FSUIPCs lua plugin debug logging facilities, and also log offsets 0x0350/0x0352 as hex values 

[Isak]

Thank you, John, for the clarification regarding the offsets. I have modified the Lua script accordingly to use 0x311E for NAV1 standby.

The current Lua script (RadioTest.lua) is intended solely for testing the setting of the NAV1 standby frequency. Here is the script:

dev = com.open("COM6", 115200, 0)  -- Open COM port with baud rate 115200
ipc.display("Lua script is running...", 3)

function processInput()
    local datastring, length = com.read(dev, 256)
    
    if length then
        ipc.log("Raw data received: '" .. datastring .. "' [" .. length .. "]")
        
        if datastring:match("^NAV1SB") then
            local frequencyStr = datastring:match("NAV1SB%s*(%d+%.%d+)")  -- Extracts the frequency
            
            if frequencyStr then
                ipc.log("Extracted frequency: " .. frequencyStr) -- Debug log
                
                local bcdValue = convertToBCD(frequencyStr)
                
                ipc.log("BCD Converted: " .. string.format("0x%X", bcdValue)) -- Debug log
                
                ipc.writeUD(0x311E, bcdValue)  -- Send to FSUIPC
                
                ipc.display("NAV1 standby set: " .. frequencyStr, 3)
                ipc.log("NAV1 standby frequency set to BCD: " .. string.format("0x%X", bcdValue))
            else
                ipc.log("Error: Failed to extract frequency!")
            end
        end
    end
end

-- Convert frequency to BCD (e.g., "113.45" → 0x1345)
function convertToBCD(freq)
    local cleanFreq = freq:gsub("%.", "")  -- Remove decimal (e.g., "109.2" → "0920")
    local bcd = tonumber(cleanFreq, 10)    -- Convert to number
    return bcd or 0  -- Return 0 if conversion fails
end

while true do
    processInput()
    ipc.sleep(100)
end

And here is the Arduino code:

#include <Keypad.h>
#include <LiquidCrystal.h>

// Initialize the LCD connected to pins 9, 8, 7, 6, 5, 4 on Arduino
LiquidCrystal lcd(9, 8, 7, 6, 5, 4);

// Keypad settings
const byte ROWS = 4; // four rows
const byte COLS = 4; // four columns
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {A0, A1, A2, A3}; 
byte colPins[COLS] = {A4, A5, A6, A7}; 

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

String frequency = "1";  // Pre-define the first digit as '1'

void setup() {
  lcd.begin(20, 4); 

  // Turn off the display:
  lcd.noDisplay(); delay(500);
  // Turn on the display:
  lcd.display();
  
  // Initial LCD message:
  lcd.setCursor(0, 0);
  lcd.print("Keypad Radio");
  delay(4000);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Frequency to send:");
  
  Serial.begin(115200); //start checking serial connection
}

void loop() {
  char key = keypad.getKey();
  if (key) {
    if (key == 'A') {
      sendCom1FrequencyToSim();
      frequency = "1";  // Reset to '1' after sending
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Frequency to send:");
    }
      else if (key == 'B') {
      sendCom2FrequencyToSim();
      frequency = "1";  // Reset to '1' after sending
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Frequency to send:");
    }
      else if (key == 'C') {
      sendNav1FrequencyToSim();
      frequency = "1";  // Reset to '1' after sending
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Frequency to send:");
    }
      else if (key == 'D') {
      sendNav2FrequencyToSim();
      frequency = "1";  // Reset to '1' after sending
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Frequency to send:");
    }
     else if (key == '*') {
      if (frequency.length() > 1) {  // Ensure '1' stays as the first digit
        frequency.remove(frequency.length() - 1); // Remove last digit
        
        // Clear the previous frequency display and update it
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Frequency to send:");
        lcd.setCursor(0, 2);
        lcd.print(formatFrequency(frequency));
      }
    }
//     else if (key == 'D') {
//      transferFrequency();  // Trigger COM1 STBY RADIO SWAP
//    }
     else if (isDigit(key)) {
      if (frequency.length() < 6) {  // limit to 6 digits (including '1')
        frequency += key;
        
        // Update the LCD with the new frequency
        lcd.setCursor(0, 2);
        lcd.print(formatFrequency(frequency));
      }
    }
  }
}

String formatFrequency(String freq) {
  // Automatically add the decimal point at the right place
  if (freq.length() >= 4) {  // Adjusted to account for the pre-defined '1'
    return freq.substring(0, 3) + "." + freq.substring(3);
  }
  return freq;  // If less than 3 digits, no decimal
}

void sendCom1FrequencyToSim() {
  String formattedFrequency = formatFrequency(frequency);  // Add the decimal point
  Serial.print("COM1SB ");  // Add COM1SB tag
  Serial.println(formattedFrequency);  // Send formatted frequency (with decimal)
}

void sendCom2FrequencyToSim() {
  String formattedFrequency = formatFrequency(frequency);  // Add the decimal point
  Serial.print("COM2SB ");  // Add COM2SB tag
  Serial.println(formattedFrequency);  // Send formatted frequency (with decimal)
}

void sendNav1FrequencyToSim() {
  String formattedFrequency = formatFrequency(frequency);  // Add the decimal point
  Serial.print("NAV1SB ");  // Add NAV1SB tag
  Serial.println(formattedFrequency);  // Send formatted frequency (with decimal)
}

void sendNav2FrequencyToSim() {
  String formattedFrequency = formatFrequency(frequency);  // Add the decimal point
  Serial.print("NAV2SB ");  // Add NAV2SB tag
  Serial.println(formattedFrequency);  // Send formatted frequency (with decimal)
}

//void transferFrequency() {
//  Serial.println("COM1TX");  // Send transfer command
//}

Below is an excerpt from the RadioTest.log file, showing what happens when I attempt to send 109.2, 109.20, and 109.200:

3506422 LUA: Local: datastring = NAV1SB 109.2

  3506422 LUA: Local: length = 14
  3506438 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:8 fn: processInput
  3506438 LUA: Raw data received: 'NAV1SB 109.2
' [14]
  3506438 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:10 fn: processInput
  3506438 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:11 fn: processInput
  3506438 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:13 fn: processInput
  3506438 LUA: Local: frequencyStr = 109.2
  3506438 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:14 fn: processInput
  3506438 LUA: Extracted frequency: 109.2
  3506453 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:16 fn: processInput
  3506453 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:33 fn: convertToBCD
  3506453 LUA: Local: freq = 109.2
  3506453 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:34 fn: convertToBCD
  3506453 LUA: Local: cleanFreq = 1092
  3506453 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:35 fn: convertToBCD
  3506453 LUA: Local: bcd = 1092
  3506453 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:18 fn: processInput
  3506469 LUA: Local: bcdValue = 1092
  3506469 LUA: BCD Converted: 0x444
  3506469 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:20 fn: processInput
  3506485 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:22 fn: processInput
  3506500 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:23 fn: processInput
  3506500 LUA: NAV1 standby frequency set to BCD: 0x444

3512375 LUA: Local: datastring = NAV1SB 109.20

  3512375 LUA: Local: length = 15
  3512375 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:8 fn: processInput
  3512375 LUA: Raw data received: 'NAV1SB 109.20
' [15]
  3512375 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:10 fn: processInput
  3512391 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:11 fn: processInput
  3512391 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:13 fn: processInput
  3512391 LUA: Local: frequencyStr = 109.20
  3512391 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:14 fn: processInput
  3512391 LUA: Extracted frequency: 109.20
  3512391 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:16 fn: processInput
  3512391 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:33 fn: convertToBCD
  3512391 LUA: Local: freq = 109.20
  3512407 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:34 fn: convertToBCD
  3512407 LUA: Local: cleanFreq = 10920
  3512407 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:35 fn: convertToBCD
  3512407 LUA: Local: bcd = 10920
  3512407 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:18 fn: processInput
  3512407 LUA: Local: bcdValue = 10920
  3512407 LUA: BCD Converted: 0x2AA8
  3512422 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:20 fn: processInput
  3512422 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:22 fn: processInput
  3512438 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:23 fn: processInput
  3512453 LUA: NAV1 standby frequency set to BCD: 0x2AA8

3518438 LUA: Local: datastring = NAV1SB 109.200

  3518438 LUA: Local: length = 16
  3518438 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:8 fn: processInput
  3518453 LUA: Raw data received: 'NAV1SB 109.200
' [16]
  3518453 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:10 fn: processInput
  3518453 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:11 fn: processInput
  3518453 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:13 fn: processInput
  3518453 LUA: Local: frequencyStr = 109.200
  3518453 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:14 fn: processInput
  3518453 LUA: Extracted frequency: 109.200
  3518453 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:16 fn: processInput
  3518469 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:33 fn: convertToBCD
  3518469 LUA: Local: freq = 109.200
  3518469 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:34 fn: convertToBCD
  3518469 LUA: Local: cleanFreq = 109200
  3518469 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:35 fn: convertToBCD
  3518469 LUA: Local: bcd = 109200
  3518469 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:18 fn: processInput
  3518469 LUA: Local: bcdValue = 109200
  3518485 LUA: BCD Converted: 0x1AA90
  3518485 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:20 fn: processInput
  3518500 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:22 fn: processInput
  3518516 LUA: ...\Documents\Prepar3D v5 Add-ons\FSUIPC6\RadioTest.lua:23 fn: processInput
  3518516 LUA: NAV1 standby frequency set to BCD: 0x1AA90

 

Unfortunately nothing happens with the Nav1 standby frequency in the simulator.

Cheers,

Isak

[John Dowson]

11 hours ago, Isak said:

Below is an excerpt from the RadioTest.log file, showing what happens when I attempt to send 109.2, 109.20, and 109.200:

Isn't the error obvious?

11 hours ago, Isak said:

  3506469 LUA: Local: bcdValue = 1092
  3506469 LUA: BCD Converted: 0x444
...
  3512407 LUA: Local: bcdValue = 10920
  3512407 LUA: BCD Converted: 0x2AA8
...
  3518469 LUA: Local: bcdValue = 109200
  3518485 LUA: BCD Converted: 0x1AA90

BCD for 109.20 would be 0x0920 (leading 1 omitted). You are converting the value to hex, not BCD.

[Isak]

Thank you for your help! I’m not very experienced in coding, so the error wasn’t obvious to me. But with your explanation, I now see where I went wrong and should be able to get it working. I’ll report back soon.

[Isak]

Hi John,

As I mentioned, I wouldn’t call myself a "coder," so I often rely on ChatGPT for help. But when I get stuck, I turn to the forum for deeper insights. Thanks to your hints and guidance, I now have a working script again. I really appreciate your help—thank you so much!

Best regards,
Isak

Here is the working lua script:

dev = com.open("COM6", 115200, 0)  -- Open COM port with baud rate 115200
ipc.display("Lua script is running...", 3)

function processInput()
    local datastring, length = com.read(dev, 256)
    
    if length then
        ipc.log("Raw data received: '" .. datastring .. "' [" .. length .. "]")
        
        if datastring:match("^NAV1SB") then
            local frequencyStr = datastring:match("NAV1SB%s*(%d+%.%d+)")  -- Extracts the frequency
            
            if frequencyStr then
                ipc.log("Extracted frequency: " .. frequencyStr) -- Debug log
                
                local bcdValue = convertToBCD(frequencyStr)
                
                ipc.log("BCD Converted: " .. string.format("0x%X", bcdValue)) -- Debug log
                
                ipc.writeUD(0x311E, bcdValue)  -- Send to FSUIPC
                
                ipc.display("NAV1 standby set: " .. frequencyStr, 3)
                ipc.log("NAV1 standby frequency set to BCD: " .. string.format("0x%X", bcdValue))
            else
                ipc.log("Error: Failed to extract frequency!")
            end
        end
    end
end

-- Convert frequency to BCD (e.g., "113.45" → 0x1345)
function convertToBCD(freq)
    local cleanFreq = freq:gsub("%.", "")  -- Remove decimal (e.g., "109.2" → "0920")
    local decimalNumber = tonumber(cleanFreq) -- Convert to number

    if not decimalNumber then return 0 end -- Return 0 if conversion fails

    local bcd = 0
    local shift = 0

    -- Convert each decimal digit to BCD format
    while decimalNumber > 0 do
        local digit = decimalNumber % 10
        bcd = bcd + (digit * (16 ^ shift)) -- Use base 16 shift instead of bitwise left shift
        decimalNumber = math.floor(decimalNumber / 10)
        shift = shift + 1
    end

    return bcd
end


while true do
    processInput()
    ipc.sleep(100)
end